Adjustable stator blade and shroud ring arrangement for axial flow turbines and compressors



March 9, 1954 2,671,634

ADJUSTABLE STATOR BLADE AND, SHROUD RING ARRANGEMENT F. W. W. MORLEY Filed June so, 1950 FOR AXIAL FLOW TURBINES AND COMPRESSORS u 5 Sheets-Sheet l NVENOE 5mm Maem' b MW March 9, 1954 Filed June 30, 1950 EMENT 5 Sheets-Sheet 2 a ay 1% my y x! w I 1 19a I l' .4

. w x2 23 Fig.5,2021 2-3".

E m M Matti) *z xxx-MW a INVEIITN.

March 9, 1954 A .w. w. MORLEY 2.671.634

, ADJUSTABLE STAT BLADE AND SHROUD RING ARRANGEMENT FOR AXIAL FLOW TURBIYNES AND COMPRESSORS Filed June so, 1950 5 sheets-sheet s El a a v .1 i L." l

i I Q I AIL 4A l A z- I mvzn'tol. 19 2% M02465 March 9, 1954 2,671,634 magr cmmu'r.

F. W. W. MORLEY ADJUSTABLE STATOR BLADE AND SHROUD RING FOR AXI Filed June 30, 1950 AL FLOW TURBINES AND COMPRESSO 5 Sheets-Sheet 4 mam-om E w, m M0241? M r h 1954 F. w. w. MORLEY 2.671.634

ADJUSTABLE STATOR BLADE AND SHROUD R ARRANGEMENT AXIAL F0 FLOW TURBINES AND CO ESSORS Filed June 30, 1950 5 Sheets-Sheet 5 c WMWM Patented Mar. 9, 1954 ADJUSTABLE STATOR BLADE AND SHROUD RING ARRANGEMENT FOR AXIAL FLOW TURBINES AND COMPRESSORS Frederick William Wa Trent, Derby, Englan Limited, Derby, Eng

lton Morley, Aston-ond, assignor to Rolls-Royce land, a British company Application June 30, 1950, Serial No. 171,344 Claims priority, applicagigi Great Britain 8 Claims. (01. 25349) This invention relates to axial-flow turbines and compressors and is concerned with axialflow turbines and compressors of the type (hereinaiter referred to as axial-flow turbines or com-= pressors of the type specified) comprising a ring otstator blades so mounted that their pitch is adjustable. Such an arrangement is described in the specification of U. S. Patent No. 2,613,029 (G. L. Wilde).

This invention has for an object to provide an improved construction of axial-flow turbine 01' compressor of the type specified in which the difllculties experienced in supporting the inner shroud or the adjustable blading, are avoided.

According to this invention, an axial-flow turbine or compressor of the type specified has some only of the blades 01 a ring of adjustable stator blades mounted in the outer casing of the compressor or turbine, each through an associated bearing arrangement having a substantial effective length axially or the blade, to extend inwardly from the outer casing and by their inner ends to support cantileverwise a shroud ring for the ring of blades, and has the remaining blades of the ring of blades engaged with the inner shroud ring and the outer casing through simple journal bearings which provide no substantial support for the inner shroud ring. For example in a construction having a ring of. say. 67 adjustable stator blades, 8 of these blades may be arranged to carry the inner shroud ring cantileverwise from the outer casing and the remaining 59 blades may have short spindles engaged in simple cylindrical bushes or hearing sockets in the outer casing and inner shroud ring.

According to a feature oi this invention, a bearing arrangement for the inner shroud ring supporting blades may comprise ball thrust bearings spaced apart in a direction lengthwise or the blade. The thrust bearings locate the supporting blades radially within the outer casing and the innerends oi the supporting blades consequently locate the inner shroud ring centrally within the outer casing.

According to another featur or this invention, in a construction of turbine or compressor whereof the casing is formed in a number of parts, say two semi-cylidrical or the like parts, the inner shroud ring is formed in a corresponding number of part-circular portions which are mounted separately in the corresponding casing parts during assembly and abut by their ends to form a complete shroud ring on assembly together of the casing parts. Each part-circular portion of the inner shroud ring may be divided into two on a transverse plane through the bearing sockets for the inner ends of the ring of adjustable stator blades to facilitate assembly of the blades in the shroud ring, and the two parts of each part-circular portion of the inner shroud ring will in such a, case be secured together as by bolting after assembly of the stator blades.

According to yet another feature of this invention, those stator blades of the ring of adjustable stator blades which support the inner shroud ring may be formed from a material difierent from that of the remaining stator blades; for example the supporting stator blades may be formed from stee1 and the remaining stator blades may be made from an aluminium alloy.

According to yet another feature of this in=- vention, the thrust bearings above referred to may be pre-Jcaded.

The number and location of the supporting stator blades may be varied as desired and conveniently they will be distributed substantially uniformly around the ring of blades.

The arrangement of this invention is especially suitable for supporting the inner shroud of a ring of adjustable stator blades located between two stages of rotating blading, since in this case the inner shroud ring cannot be readily supported from other stationary parts of the compressor or turbine structure.

A construction of axial-flow compressor will now be described which ha between two stages of rotating blades a ring of stator blades, the angle of attack of which can b varied, for the purpose, for example, of preventing stalling of the compressor when running at a speed substantially different from its designed running speed, by turning the blades about their radial axes. The description makes reference to the accompanying drawings in which:

Figure 1 illustrates the axial-flow compressor with rts of the periphery broken away,

Fig fie 2 is a section showing part of a ring of adjustable stator blades,

pressor casing.

'Figures 3, 4, are sections on the lines 3-3, 4-4, and 5-5 respectively ofFigure 2, and

Figure 6 is a section on the line 8-6 of F18- ure 3.

' Referring to Figure l, the casing of the axialflow compressor comprises two substantially semi-cylindrical parts III, II which in assembly are bolted together over flanges I2. The compressor comprises between two rings I3, ll of rotor blades a ring of adjustable stator blades ome of which are referenced lid, and of which the remainder are referenced Iib.

Each of the adjustable blades Iia, lib of the ring of guide blades is formed with an integral outer platform I i from the outer surface of which projects a supporting splindle Ila, Ilb

respectively, the platforms I8 together forming the outer shroud ring of the ring of blades. Each blade Iia'or lib is also formed at its inner end with a stub spindle I8 by which the blade engageswith an inner shroud ring I9 in a manner permitting it to rotate freely about its radial axis.

The inner shroud ring I! for the ring of adjustable blades Iia, lib is formed in two semicircular halves I9a, lib which are respectively allocated to the two parts I0, II of the comof the inner shroud ring are formed with pro,- jecting ribs 20 (Figure 2) which spigot into suitably shaped recesses 2I in the ends of the other half Iia of the shroud ring so as to locate the two halves accurately with respect to one another on assembly 'of the two parts I0, II of the compressor casing. The radial forces at the junction of the two halvw, Isa, lib, due to the resultants of the tangential loads on the statorblades, are thereby accommodated.

The inner shroud ring I9 is formed with a plurality of radial bores 22 which are enlarged at their radially outer ends, and the bores 22 receive the spindles It provided on the inner ends of the adjustable guide blades Iia, lib. To facilitate assembly of the blades and their engagement in the radial bores 22, each half I9a, lib of the inner shroud ring I9 is split on a transverse plane (see Figure 5) so that the parts of each half can be assembled to the inner ends .01. the blades after they have been placed in position in the appropriate part of the compressor casing and prior to assembly together of the two parts I0, II of the compressor casing. The parts of each half of the inner shroud ring I9 are secured together by bolts 23.

The adjustable blades associated with each part of the compressor casing are divided into two sets Iia, lib of which the set of blades Iia have elongated spindles Ila on their outer platforms I6 and the set of blades Iibhave plain cylindricalspindles Ilb. In a ring of 67 adjust-' able blades, for example, 8 of the blades may be provided with elongated spindles Ila, four being allocated to each half of the compressor casing.

The blades Iia with elongated spindles Ila are so arranged within the outer casing of the compressor that their spindles project into radial recesses in bosses 24 (Figures 2 and 3) formed on the outer casing and the spindles Ila are located within the recesses lengthwise of the blades through two deep groove ball journal bearings 25, 26 which also act as thrust bearings. The inner races of bearings 25 fit on the spindles Ila adjacent the platform Ii on the blades Iia and the inner races of bearings 26 fit on the spindles Ila adjacent their free ends. The inner races of,

The end faces of one half lab.

- 4 bearings 2i, 2! may be pre-loadedtowards one another in the direction of their axes by Thackeray washers ll. The blades Iia with elongated spindles Ila will be distributed substantially uniformly around the compressor casing. Covers Ila are provided for the outer ends of the bores in bosses 24.

The blades Iib'having the stub spindles Ilb at their outer ends are distributed in the spaces between the blades Iia having the elongated spindles Ila and the spindles Ilb are engaged with the outer casing of the compressor through cylindrical bearing bushes 29 which are let into radial bores 30 in the wall of the outer casing.

The bores in the bushes 28 extend only part way ends of blades Iia' engaging with the bearing bores formed in the inner shroud ring I9. The remaining blades lib of the ring of adjustable blades are supportedin eil'ect loosely between 'the inner shroud ring I9 and the outer casing III, II of the compressor, and do not make any substantial contribution to the support of the shroud ring I9. I

It is preferred that the blades I ia having elongated spindles Ila be made from a material such as steel and that the remaining blades lib be made from a material such as aluminium alloy.

It will be appreciated that by suitably selecting the number and position of the blades lia the inner shroud ring I! may be located against radial and rotational movement. The additional weight of elongated spindles Ila and bearing means ii, 16 may, thereby be avoided on the majority'of blades.

The following arrangement is provided in the illustrated construction for adjusting the angle of attack of guide blades.

I the inner surface of an operating ring 33 mounted within a groove in a thickened part II of the compressor casing as'to rotate about the axis of the compressor. When the ring it is rotated it constrains the peg 30 on each of the adjustable blades Iia. lib to be displaced in a direction circumferentially of the compressor casing I0, I I, thus rotating the blades about their radial axes. The cylindrical pieces II above referredto swivel on the operating pegs and also slide in the axial part-cylindrical recesses 32 in which they are received. As will be seen from Figure 6, the ring 33 is made in two halves having recesses 35 in their abutting ends to receive springs ii for transmitting movement of one nected with a suitable control, illustrated as a ram 4|.

The operating ring 33 is located both axially and radially within the groove in the compressor may be larger-than the remainder. The larger rollers 42 are arranged to co-operate with local radially and circumferentially extending grooves 45 formed in the outer surfaces of the operating ring 33, thereby to provide radial and axial location of the ring, while the smaller rollers (not shown) run on the outer peripheral surface of the ring -33 and provide radial location therefor.

The bearing bushes 29 for the stub spindles Nb, and the rollers 42 for locating the operating ring 83 are conveniently formed from a material preferably received in suitably shaped recesses in the casing so that their radially inner surfaces form a smooth continuation of the adjacent parts of the compressor annulus, and the recesses receiving the platforms and the axiallyspaced ends of the platforms are curved about the radial axis of the associated blade to permit the platform to swing with the blade. A small clearance is provided between adjacent platforms for the same purpose.

I claim:

1. In an axial-flow fluid machine a stator structure comprising a plurality of stator blades and means to support said stator blades in circumferentially spaced relation, comprising an annular outer casing structure, each blade having at its outer end a radially-extending spindle, the radial extent of some of the spindles being greater than that of the remaining spindles, a plurality of circumferentially-spaced journal thrust bearings supported in the outer casing structure with their axes radial, there being one such journal thrust bearing for each of the spindles having the greater radial extent to support the associated spindle rotatively in the outer .engaged rotatively thereby.

2. A stator structure as claimed in claim 1, having each said journal thrust bearing comprising a pair of ball thrust bearings mounted on the associated spindle at locations spaced apart lengthwise of the spindle.

3. A stator structure as claimed in claim 1,

1 having each said simple journal bearing comprising a bush having a cylindrical bore therein v to be engaged by the associated spindle.

4. A stator structure as claimed in claim 1,

having said inner shroud structure comprising a ring with a plurality of circumferentiallyspaced radial bores, there being a bore to afford each of said bearings for said radial spindles at the inner ends of the stator blades.

5. A- stator structure as claimed in claim 1,

having said'inner shroud structure comprising a ring with a plurality of circumferentiallyspaced radial bores, there being a bore to aflord each of said bearings for said radial spindles at the inner ends of the stator blades, said ring being formed in. abutting parts whereof the plane of abutment extends through each of the bores so that each ring part has formed in it a plurality of half bores.

I 6. In an axial-flow fluid machine having a stator structure formed in a number of segments I arranged together to form a complete annulus of stator blading, a construction of said segments comprising a plurality of circumferentiallyspaced stator blades, and a part-annular inner shroud structure and a part-annular outer casing structure, said blades being supported in said inner shroud structure and said outer casing structure in circumferentially-spaced relation, each said blade being rotatively adjustable about its lengthwise axis by each blade having at its outer end a radially-extending spindle, the radial extent of some of the spindles being greater than that of the remaining spindles, a plurality of journal thrust bearings, one for each of said spindles having the greater radial extent to support the associated spindle rotatively in the outer casing structure with the spindle axis radial to the axis of the outer casing structure, a plurality of simple journal bearings, one for each of said remaining spindles to position the associated spindle circumferentially in the outer casing. structure with the spindle axis radial to the axis of the outer casing structure, and a radial spindle at the inner end of each of said blades, said spindles at the inner ends of the blades being engaged rotatively in the inner shroud structure with their axes radial to the axis of the inner shroud structure. I

. 7. In an axial-flow fluid machine, a stator casing, a rotor rotatively mounted in said stator casing, a plurality of axially-spaced rows of rotor blades mounted on the periphery of said rotor to rotate therewith, a row of stator blades mounted in said stator casing between a pair of said rows of rotor blades, each stator blade of said row having at each of its ends a longitudinallyextending spindle, the spindle at one end being aligned with the spindle at the other end, a plurality of outer bearings provided in circumferentially-spaced relation in said stator casing, there being an outer bearing for each blade of said row of stator blades and each outer bearing having its axis radial to the machine axis, and an annular inner shroud structure encircling said rotor between said two rows of rotor blades, a plurality of inner bearings provided in circumferentially-spaced relation in said inner shroud structure, there being one inner bearing for each blade of said row of stator blades and each inner bearing having its axis radial, each blade of the row of stator blades having the spindle at one of its ends rotatively engaging an outer hearing and the spindle at the other of its ends rotatively engaging an irmer bearing, whereby said inner shroud structure is supported from and maintained concentric with said stator casing solely by said row of stator blades.

8. A stator structure as claimed in claim 7,

7 having said inner shroud structure comprising Number a ring with a plurality of circumierentialiy- 2,455,251 spaced radial bores, there being a bore for each 2,460,778 01' the radial spindles at the inner ends of the 2,472,062 stator blades, said rinz'being formed in abutting 5 2,473,329 parts whereof the plane or abutment extends 2,488,875 through each of the bores, so that each ring part 2,500,070 has formed in it a plurality of half bores.

FREDERICK WILLIAM WALTON MORLEY.

' 10 Number References Cited in the tile 0! this patent 579,585 UNITED STATES PATENTS 629,770 Number Name Date 823341 1,880,737 Hodgkinson Aug.14, 1928 2,443,263 Meyer June 15, 1948 ame Date Hersey Nov. 00, 1040 Willzoos m1. 1, 1040 Boestad June 7, 1040 Candler June 14, 1040 Morley Nov. 22, 1949 Hagen liar. 7, 1000 FOREIGN PATENTS Country Date Germany July 1, 1933 Great Britain Sept. 28, 1040 France Oct. 18, 1037 France June 21. 1060 

